Suppression of phase separation in InGaN layers grown on lattice-matched ZnO substrates

• Published in: Journal of crystal growth Vol. 311; no. 22; pp. 4628 - 4631
• Main Authors: Li, Nola, Wang, Shen-Jie, Park, Eun-Hyun, Feng, Zhe Chuan, Tsai, Hung-Lin, Yang, Jer-Ren, Ferguson, Ian
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.11.2009; Elsevier
• Subjects: A1. High-resolution X-ray diffraction; A1. Phase separation; A3. Metalorganic chemical vapor deposition; B1. Nitrides; B1. Sapphire; B1. ZnO; Buffers; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Crystal growth; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Gallium nitrides; Indium; Indium gallium nitrides; Materials science; Methods of crystal growth; physics of crystal growth; Methods of deposition of films and coatings; film growth and epitaxy; Phase separation; Physics; Sapphire; Solubility, segregation, and mixing; phase separation; Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation; Zinc oxide; A1. High-resolution X-ray diffraction; B1. Nitrides; A3. Metalorganic chemical vapor deposition; A1. Phase separation; B1. Sapphire; B1. ZnO; 81.15.Gh; 81.05.Ea; XRD; Gallium nitride; Thin films; Stress relaxation; Sapphire; Zinc oxide; Indium nitride; Mechanical properties; Indium; MOCVD; Silicon additions; III-V compound; Interfaces; Transmission electron microscopy; Phase separation; Growth mechanism; III-V semiconductors
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2009.09.004

Sapphire and SiC are typical substrates used for GaN growth. However, they are non-native substrates and result in highly defective materials. The use of ZnO substrates can result in perfect lattice-matched conditions for 22% indium InGaN layers, which have been found to suppress phase separation compared to the same growths on sapphire. InGaN layers were grown on standard (0 0 0 2) GaN template/sapphire and (0 0 0 1) ZnO substrates by metalorganic chemical vapor deposition. These two substrates exhibited two distinct states of strain relaxation, which have direct effects on phase separation. InGaN with 32% indium exhibited phase separation when grown on sapphire. Sapphire samples were compared with corresponding growths on ZnO, which showed no evidence of phase separation with indium content as high as 43%. Additional studies in Si-doping of InGaN films also strongly induced phase separation in the films on sapphire compared with those on ZnO. High-resolution transmission electron microscopy results showed perfectly matched crystals at the GaN buffer/ZnO interface. This implied that InGaN with high indium content may stay completely strained on a thin GaN buffer. This method of lattice matching InGaN on ZnO offers a new approach to grow efficient emitters.